Switchgear with fuses individually mounted on fuse carriers and switches therefor for interlocks

ABSTRACT

High voltage fuses are mounted on individual carriers for movement into and out of engagement with stationary contacts under the control of a carriage that can be connected to any or all of the carriers. Switches are arranged to connect any or all of the fuses in circuits. A locking bolt holds each fuse carrier in closed position and can be moved to locking position only when the fuse carrier is closed. Interlocks between the fuse carriers and operators for the switches prevent opening the carrier when the switches are closed and closure of the switches when the carriers are open.

United States Patent 1 91 1 1 3,790,861 Sakats I Feb. 5, 1974 SWITCHGEARWITH FUSES 3,339,118 8/1967 Hamer 317/114 INDIVIDUALLY MOUNTED 0N FUSE3,576,509 4/1971 Bernatt 337/8 Harry 3 l FOR INTERLOCKS Gerald Sakats,Arlington Heights, 111.

S & C Electric Company, Chicago, Ill.

Filed: Oct. 10, 1972 Appl. No.: 295,826

Inventor:

Assignee:

References Cited UNITED STATES PATENTS 5/1971 Keough 317/114 PrimaryExaminer-James R. Scott Assistant Examiner-Gerald P. Tolin Attorney,Agent, or Firm-Kirkland & Ellis 5 7] ABSTRACT High voltage fuses aremounted on individual carriers for movement into and out of engagementwith stationary contacts under the control of a carriage that can beconnected to any or all of the carriers. Switches are arranged toconnect any or all of the fuses in circuits. A locking bolt holds eachfuse carrier in closed position and can be moved to locking positiononly when the fuse carrier is closed. Interlocks between the fusecarriers and operators for the switches prevent opening the carrier whenthe switches are closed and closure of the switches when the carriersare open.

1 Claims, neEis les PATENTED FEB 5 I974 SHEET 10F 7 sum s or 7 gPATENTED FEB 51914 HM J PAIENIEHFEB i n 3.790.861

SHEET 7 BF 7 1 SWITCHG-EAR WITH FUSES-INDIVIDUALLY MOUNTED ON FUSECARRIERS AND SWITCHES THEREFOR FOR INTERLOCKS out-of operativeposition'underthe control of acarriage arrangedzto move anyrorlallofthe-carriers to and from the operative position; :to lock each carrierin its .fuse

closedzposition and to permit operationof the lock only when the carrieris in the closed position; to lock the carriage securely to the carrieror-carriersto be withdrawn; to provide a switch foreach fuse and anoperator for each switch; and -to interlock each fuse carrier and therespective switch operator to prevent opening of the carrier when theswitch is closed and to prevent closing of the switch when the carrieris open.

In the drawings: FIG. 1 is a perspective view of a portion of switchgearin which the present invention is embodied, one of the fuse carriersbeing shown in the withdrawn position by the carriage in a correspondingposition.

FIG. 2 is a horizontal sectional view taken generally along line 2-2 ofFIG. 1.

FIG. 3 is a view, in front elevation, of the construction shown in FIG.2.

FIG. 4 is a horizontal sectional view at an enlarged scale takengenerally along line 44 of FIG. 3.

FIG. 5 is a view, in front elevation, of the construction shown in FIG.4.

FIG. 6 is a vertical sectional view taken generally along line 6--6 ofFIG. 5.

FIG. 7 is a perspective view of one of the striker plates.

FIG. 8 is a vertical sectional view taken generally along line 88 ofFIG. 1.

FIG. 9 is a vertical sectional view taken generally along line 9-9 ofFIG. 8.

FIG. 10 is a vertical sectional view at an enlarged scale takengenerally along line 10-10 of FIG. 8.

FIG. 11 is a plan view of one of the handles and the associated lockingcam mounted thereon.

FIG. 12 is a top plan view of the locking cam.

FIG. 13 is a perspective view of the locking cam showing the inclinedcam surfaces.

FIG. 14 is an elevational view of the locking bolt actuator.

FIG. 15 is a view, in side elevation looking from left to right of thelocking bolt. actuator shown in FIG. 14.

FIG. 16 is a horizontal sectional view at an enlarged scale takengenerally alongline 16-l6 of FIG. 14.

FIG. 17 is a view, in front elevation, of the switch interlock means.

FIG. 18 is a view of the switch interlock means shown in FIG. l7'lookingfrom right to left, the switch interlock'means being shown in the switchclosed position.

'FIG. 19 is a view, similar to FIG. 17, but showing the switch interlockmeans in the switch open position.

FIG. 20 is a view, similar to FIG. 18, showing theswitch'interlock'means in the switch open position.

line contacts 13. At their other ends the fuses 11 have.

contacts 14 that are arranged to engage and disengage switch contacts 15which are connected to switch blades 16. The switch blades 16 arearranged to engage line contacts 17. Operators, indicated by brokenlines at 18, are provided for individually operating the switch blades16 from and to the switch closed positions. They are provided withmanually operable handles 19, also shown by broken lines. The operators18 can be of conventional construction such as that disclosed in Bernattet al. US. Pat. No. 3,563,102 issued Feb. 16, 1971. However, it will'beunderstood that other operators can be employed.

As will appear hereinafter the fuses 11 are individu-' ally mounted formovement into and out of engagement with the line contacts 13 and switchcontacts 15. However, provision is made for preventing movement of thefuses 11 from the engaged position as long as the respective switchblade 16 is closed. Only after the respective switch blade 16 is openedcan the corresponding fuse 1 1 be withdrawn for servicing orreplacement.

Since the various contacts and switches are of conventional constructiononly portions of them are illustrated and described herein.

Referring now to FIG. 1 it will be observed that the reference character22 designates, generally, a metallic housing that is provided with threefuse carriers each of which is indicated at 23. Each fuse carrier 23 canbe considered to comprise the fuse 11 mounted thereon and extending froman exhaust control device 24 which is carried by an insulator 25 that ismounted on a rear plate 26, FIG. 2, which forms a part of a carrierfront housing that is indicated, generally at 27. The carrier fronthousing 27 is provided with a front plate 28 and end plates 29.

In order to locate accurately the fuse carrier 23 in the housing 22,upper and lower openings 30 and 31 are provided in the rear and frontplates 26 and 28 for engagement by upper and lower locating pins 32 and33 that are mounted on angle frame members one of which is indicated at34 in FIG. 1. A reason for this accurate location of the carrier 23 andparticularly of the carrier front housing 27 with respect to the housing22 I and lower locating pins 32 and 33 are positioned on each side ofthe carrier front housing 27 so that both sides are accurately locatedwith respect to the housing 22 when the fuse carrier 23 occupies theinserted or fuse closed position.

It is desirable that any one or two or all three of the fuse carriers 23be arranged to be withdrawn and re placed from and in the housing 22.For this purpose a carriage, indicated generally at 38, is employed. Thecarriage 38 comprises upper and lower channel shaped frame members .39and 40 that are suitably slidably mounted in the housing 22. As will beunderstood readily the channel shaped frame members 39 and 40 are somounted within the housing 22 that they move along the predeterminedpath with respect to the housing 22 and with a minimum of deviationtherefrom. The frame members 39 and 40 are interconnected by a verticalpanel 41 on which handles 42 are pivoted for controlling the operationof a locking mechanism individual to each of the fuse carriers 23. Asshown in FIG. 11 each handle 42 has a spacer sleeve 43 extendingtherefrom and also a shaft 44. At the inner end of the shaft 44 there isa locking cam 45, FIGS. 8, 12 and 13 which is secured against rotationby a key 46. As shown in FIG. 9 a bearing sleeve 47 is secured to therear side of the panel 41 and provides a bearing support for therespective shaft 44. As seen in FIGS. 1 and 9 an opening 48 is providedin the front plate 28 of each fuse carrier 23 to permit the insertion ofthe locking cam 45 of the respective handle 42 therethrough.

As illustrated in FIGS. 3, 4, 5, l4, l and 16 a cam receiving slot 49 isprovided in a circular locking bolt actuator 50 which is pivotallymounted between the rear and front plates 26 and 28 of the carrier fronthousing 27. It will be understood that the cam receiving slot 49 is ofabout the same dimensions as the opening 48 in the front plate 28. Alsothe cam receiving slot 49 is only slightly larger than the locking cam45 with the clearance therebetween being only that necessary tofacilitate entry and withdrawal of the locking cam 45 to and from thecam receiving slot 49.

i The locking bolt actuator 50 is pivotally mounted on the rear side ofthe front plate 26 by means of pins 51 that extend rearwardly therefromand are secured as by welding thereto. The pins 51 extend througharcuate slots 52 in the locking bolt actuator 50 and have heads 53 attheir distal ends that are located in arcuate slots 54 which aresubstantially wider than the arcuate slots 52. Circular openings 54' atone end of each of the arcuate slots 54permit entry of the heads 53 intothe arcuate slots 54. Pivotally secured to diametrically oppositelocations on the locking bolt actuator 50 are links 55. They are movableendwise and with respect to slots 55 in the periphery of the lockingbolt actuator 50. The other ends of the links 55 are pivotally connectedto endwise movable locking bolts-56 which are guided for translatorymovement by guides 57. Only one of the guides 57 is illustrated in FIGS.4 and 5 of the drawings.

" As here shown, openings 58 are provided in the end plates 29 throughwhich the locking bolts 56 are movable. Also they are movable throughopenings 59 in the angle frame members 34. When the locking bolts 56 areextended, as shown in FIGS. 4 and 5, the respective fuse carrier 23cannot be withdrawn from the housing 22.

It is desirable that the locking cam 45, when inserted into the camreceiving slot 49 in the respective locking bolt actuator 50 have arigid connection therewith. For this purpose inclined cam surfaces 62,FIGS. 12 and 13, are provided on the locking cam 45 for cooperation withinclined surfaces 63, FIGS. 4 and 7, of striker platesj64. As showninFlG. 5 the striker plates 64 are I located on the inside of the frontplate 28 above and below the opening 48 therein through which thelocking cam 45 is inserted into the cam receiving slot 49 of the lockingbolt actuator 50. In order to resist the torque that is applied when thehandle 42 is pivoted to the carrier locking position, openings 65, FIG.1, are provided in the front plate 28 for receiving locating pins 66that extend rearwardly from the vertical panel 41 as illustrated inFIGS. 8 and 10.

It will be understood that insulating barriers, not shown, may bemounted on the fuse carriers 23 and around the energized parts thereon.Brackets 67, FIG. 8, mounted on the rear plate 26 of the carrier fronthousing 27 are arranged to mount such barriers. Since they form no partof the present invention and since their showing would obscure certainparts of the present construction, they have been omitted.

In the withdrawn position of a fuse carrier 23, as shown'in FIG. 1 forexample, it is undesirable that the handle 42 in the unlocked positionbe permitted to pivot to the locked position. If such operation were notprevented, it would be possible to move the carriage 38 into the housing22 with the locking bolts 56 in the extended positions. Accordinglyinterlock levers 70, FIGS. 4, 5 and 6 are employed at each end of thecarrier front housing 27 Each interlock lever 70 is pivoted at 71 in aplane that extends at right angles to the path of the respective lockingbolt 56. A torsion spring 72 acts to bias its interlock lever 70 intothe path of the respective locking bolt 56 when the respective fusecarrier 23 is withdrawn. This is shown by broken lines in FIG. 6. Whenthe fuse carrier 23 is shifted to the closed position by a correspondingmovement of the carriage 38, the upper locating pin 32 engages thedistal end of the respective interlock lever 70 and moves it out of thepath of the respective locking bolt 56. Thereafter it is possible toshift the handle 42 from the unlocked position to the locked positionand extend the locking bolts 56 to the locked positions shown in FIGS. 4and 5. It will be understood that only a single interlock lever 70 isrequired since the locking bolts 56 are mechanically interconnectedthrough the locking bolt actuator 50. However, if desired, an interlocklever 70 can be provided for each of the locking bolts 56.

Referring now particularly to FIGS. 2 and 3 it will be noted that fuseinterlock means, indicated generally at 75, is arranged to interlockeach fuse carrier 23 with the respective switch means or switch operator18. The fuse interlock means 75 includes a notch 76 near the distal endof the locking bolt 56 for engagement by an arm 77 of an L-shapedlocking lever 78, the other arm 80 of which is secured to and pivotswith a shaft 81 that is journaled in a bearing sleeve 82. The bearingsleeve 82 is secured to a frame member 84 which forms a part of themetallic housing 22, FIG. 2. As will appear hereinafter, as long as theoperator 18 individual to the locking bolt 56 is in the switch closedposition, the arm 77 of the locking lever 78 extends through the notch76 and prevents withdrawal of the respective locking bolt 56. Thus it isnot possible to withdraw the respective fuse carrier 23 under theseconditions.

FIGS. 2 and 3 also show, generally at 86, switch interlock meansarranged to prevent closure of the respective Switchblade 16 when therespective fuse carrier 23 is not in the fully closed position with therespective locking bolt 56 in locking position. The details of theswitch interlock means 86 are shown more clearly in FIGS. 17 and 18.Here itwill be observed that an arm 87 is secured to the shaft 81 at theend opposite to that on which the locking lever 78 is secured. A link 88interconnects the arm 87 with a bell crank 89 which is suitably pivotedon the lower end of the support bracket 83. A link 90 interconnects thebell crank 89 with a sector plate 91, FIGS. 2 and 3, which is directlyconnected to and is movable with the handle 19 of the respectiveoperator 18. An arcuate slot 92 is formed in the sector plate 91 inorder to effect operation of the link 90 only near the end of theopening stroke of the handle 19. By this time the respective Switchblade16 will have been opened so that, during the final opening movement ofthe handle 19 to the open position as shown in FIG. 1, for example, thelink 90 is tensioned to act through the bell crank 89, link 88 and arm87 to shift thearm 77 of the L-shaped locking lever 78 out of the notch76 in the respectively locking bolt 56. Thereafter, the respective fusecarrier 23 can be withdrawn.

In order to prevent operation of the handle 19 and thereby of therespective switch blade 16 to the switch closed position in the absenceof the respective fuse carrier 23, provision is made for preventng anypivotable movement of the handle 19. This is accomplished through theprovision of a flipper 93 that is pivoted at 94 on cars 95 that extendfrom the bearing sleeve 82. A torsion spring 96 reacts against theflipper 93 in the absence of the respective locking bolt 56 to shift theflipper 93 into the path of the other arm 80 of the L- shaped lockinglever 78 as illustrated in FIGS. 19 and 20. This action prevents anymovement of the locking lever 78. Since it is connected through theswitch interlock means 86 to the sector plate 91, it is not possible topivot the handle 19 from the open position. When the respective fusecarrier 23 is returned to the fuse closed position and the respectivelocking bolt 56 is moved to the locked position, as shown in FIG. 18,the distal end engages the flipper 93 and shifts it to a position out ofthe path of the other arm 80 of the locking lever 78. Thereafter, thehandle 19 can be pivoted to close the respective switch blade 16.

FIG. 3 shows additional fuse interlock means 75 and switch interlockmeans 86 that are associated with the next fuse and switch combination.However, their operation is identical with that described hereinbefore.

With a view to preventing unauthorized access to the handles 19 for theswitches and the handles 42 for the fuses removable front panels 99,FIG. 2, can be slidably mounted on the front side of the metallichousing 22. For convenience the metallic housing 22 can be extended tothe left, as viewed in FIG. 1, to provide for receipt of equipment induplicate of that here illustrated. In such case the additional switchescan be located adjacent the switches here illustrated and the fuses canbe located at the left end of the extended housing 22.

I claim:

1. Switchgear comprising a metallic housing, a plurality of sets of fusecontacts mounted in insulated spaced relation in said housing, aplurality of unconnected fuse carriers individually removably mounted onsaid housing, a fuse carried by each of said fuse carriers for movementinto and out of contact engagement with a respective set of fusecontacts, a carriage slidably mounted on said housing independently ofand overlying said fuse carriers, coupling means on said carriage forselectively connecting said carriage to one or more of said fusecarriers for withdrawing said one or more fuse carriers and the fuse orfuses carried thereby from and returning the fuse or fuses to contactengagement with the respective set of contacts, a plurality of switchmeans in insulated spaced relation in said housing, each said switchmeans associated with a respective fuse for connecting said respectivefuses in and disconnecting said respective ruses from an electricalcircuit, switch operating means for independently operating arespectively associated switch means, and locking flipper means forpreventing operation of said switch operating means when said fusecarrier is withdrawn from said housing.

2. Switchgear according to claim 1 wherein each fuse carrier includes: alocking bolt movable into and out of locking engagement with saidhousing, and a coupling cam receiver; and said coupling means includes amanually operable coupling cam pivotally mounted on said carriageindividual to each of said fuse carriers for engaging the respectivecoupling cam receiver to cause movement of said locking bolt out oflocking engagement with said housing when said coupling cam and said camreceiver are engaged and into locking engagement with said housing whensaid coupling cam and said cam receiver are disengaged and for makingmechanical connection to the respective fuse carrier for withdrawing andreturning said fuse carrier to the housmg.

3. Switchgear according to claim 1 wherein each fuse carrier includes: alocking bolt actuator, a locking bolt connected to said actuator andmovable by said actuator into and out of lock-engagement with saidhousing, and a coupling cam receiving aperture in said actuator; andsaid coupling means includes manually operable locking cams pivotallymounted on said carriage individual to each fuse carrier for enteringthe respective aperture to engage said actuator to pivot said lockingbolt actuator to cause said locking bolt to move into and out of lockingengagement with said housing and for making mechanical connection to therespective fuse carrier for withdrawing and returning the same asaforesaid.

4. Switchgear according to claim 3 wherein said carriage comprises upperand lower frame members slidably mounted on said housing andinterconnected at one end by a vertical panel carrying said locking camson the side facing said fuse carriers, and handles on the other side ofsaid panel connected to the respective locking cams.

5. Switchgear according to claim 3 wherein aninterlock lever ispivotably mounted on each fuse carrier adjacent each of said lockingbolts and is biased with respect to said locking bolts to move into thepath of said locking bolts to prevent movement thereof to lockingposition when said fuse carrier is removed from said housing and meanson said housing for engaging each interlock lever to move the same outof said path when said fuse carrier occupies its fully closed position.

6. Switchgear according to claim 5 wherein each interlock lever ismovable in a plane parallel to the path of said carriage, and pin meanson said housing engage the respective interlock lever to move it out ofthe path of the respective locking bolt when the respective fuse carrieris slid to its fully closed position.

7. Switchgear according to claim 1 wherein guide means on said housingand on said carriage interfit with said fuse carriers to directaccurately each fuse into engagement with the set of fuse contactsindividual thereto when said fuse carriers are moved to their closedpositions.

8. Switchgear according to claim 7 wherein an interlock lever is pivotedon each fuse carrier and is biased with respect to the locking boltthereon into its path to prevent movement thereof to locking position,said guide means on said housing engaging each interlock lever to movethe same out of said paths when said fuse carrier occupies its fullyclosed position.

9. Switchgear comprising a metallic housing, a plurality of sets of fusecontacts mounted in insulated spaced relation in said housing, aplurality of unconnected fuse carriers individually slidably mounted onsaid housing, a fuse carried by each of said fuse carriers for movementinto and out of contact engagement with a respective set of fusecontacts, a carriage slidably mounted on said housing independently ofand overlying said fuse carriers, coupling means on said carriage forselectively connecting said carriage to one or more of said fusecarriers for withdrawing said one or more fuse carriers and the fuse orfuses carried thereby from and returning the fuse or fuses to contactengagement with the respective set of contacts, a plurality of switchmeans in insulated spaced relation in said housing each of said switchmeans associated with a respective fuse for connecting said respectivefuse in and disconnecting said respective fuse from a circuit, and aswitch operating means for independently operating a respectivelyassociated switch means, and fuse interlock means on each fuse carrierarranged to prevent withdrawal thereof when the switch operating meansindividual thereto is in the closed position, and locking flipper meansoperated by each switch operating means is arranged to prevent closureof its switch means when the fuse carrier individual thereto iswithdrawn from said housing.

10. Switchgear according to claim 9 wherein lost motion means betweeneach switch operating means and the respective locking flipper meanseffect operation of the latter to permit withdrawal of the respectivefuse carrier near the end of the opening stroke of said operating meansfor the respective switch means.

11. Switchgear according to claim 9 wherein each fuse carrier includes:a pivotable locking bolt actuator, a locking bolt connected to saidactuator and movable by said actuator into and out of locking engagementwith said housing, and a cam receiving slot in said actuator; and saidcoupling means includes a manually operable locking cams pivotallymounted on said carriage individual to each said fuse carriers forentering the respective slot to engage said actuator to pivot saidlocking bolt actuator from and to locking position and make mechanicalconnection to the respective fuse carrier for withdrawing and returningthe same as aforesaid; and said switch operating means includes meansfor interconnecting each locking bolt for preventing movement of therespective locking bolt to unlocked position when said switch meansoccupies the switch closed position/ 12. Switchgear according to claim11 wherein said locking bolt has a transverse notch adjacent its distalend, and said means interconnecting said locking bolt includes a lockinglever for entering said transverse notch to prevent withdrawal of saidlocking bolt and the respective fuse carrier when said switch meansoccupies the closed position.

13. Switchgear according to claim 12 wherein said locking lever isL-shaped with one arm arranged to enter said notch and the other armpivoted at its distal end and mechanically connected to the respectiveswitch operating means.

14. Switchgear-according to claim 13 wherein said locking flipper meansis a flipper biased into the path of said other arm of said L-shapedlocking lever for preventing pivotal movement thereof when therespective fuse carrier is withdrawn to prevent opening of therespective switch means, and said flipper is shifted out of the path ofsaid L-shaped locking lever by said locking bolt when the respectivefuse carrier is closed and said locking bolt occupies its lockedposition.

1. Switchgear comprising a metallic housing, a plurality of sets of fusecontacts mounted in insulated spaced relation in said housing, aplurality of unconnected fuse carriers individually removably mounted onsaid housing, a fuse carried by each of said fuse carriers for movementinto and out of contact engagement with a respective set of fusecontacts, a carriage slidably mounted on said housing independently ofand overlying said fuse carriers, coupling means on said carriage forselectively connecting said carriage to one or more of said fusecarriers for withdrawing said one or more fuse carriers and the fuse orfuses carried thereby from and returning the fuse or fuses to contactengagement with the respective set of contacts, a plurality of switchmeans in insulated spaced relation in said housing, each said switchmeans associated with a respective fuse for connecting said respectivefuses in and disconnecting said respective ruses from an electricalcircuit, switch operating means for independently operating arespectively associated switch means, and locking flipper means forpreventing operation of said switch operating means when said fusecarrier is withdrawn from said housing.
 2. Switchgear according to claim1 wherein each fuse carrier includes: a locking bolt movable into andout of locking engagement with said housing, and a coupling camreceiver; and said coupling means includes a manually operable couplingcam pivotally mounted on said carriage individual to each of said fusecarriers for engaging the respective coupling cam receiver to causemovement of said locking bolt out of locking engagement with saidhousing when said coupling cam and said cam receiver are engaged andinto locking engagement with said housing when said coupling cam andsaid cam receiver are disengaged and for making mechanical connection tothe respective fuse carrier for withdrawing and returning said fusecarrier to the housing.
 3. Switchgear according to claim 1 wherein eachfuse carrier includes: a locking boLt actuator, a locking bolt connectedto said actuator and movable by said actuator into and out oflock-engagement with said housing, and a coupling cam receiving aperturein said actuator; and said coupling means includes manually operablelocking cams pivotally mounted on said carriage individual to each fusecarrier for entering the respective aperture to engage said actuator topivot said locking bolt actuator to cause said locking bolt to move intoand out of locking engagement with said housing and for makingmechanical connection to the respective fuse carrier for withdrawing andreturning the same as aforesaid.
 4. Switchgear according to claim 3wherein said carriage comprises upper and lower frame members slidablymounted on said housing and interconnected at one end by a verticalpanel carrying said locking cams on the side facing said fuse carriers,and handles on the other side of said panel connected to the respectivelocking cams.
 5. Switchgear according to claim 3 wherein an interlocklever is pivotably mounted on each fuse carrier adjacent each of saidlocking bolts and is biased with respect to said locking bolts to moveinto the path of said locking bolts to prevent movement thereof tolocking position when said fuse carrier is removed from said housing andmeans on said housing for engaging each interlock lever to move the sameout of said path when said fuse carrier occupies its fully closedposition.
 6. Switchgear according to claim 5 wherein each interlocklever is movable in a plane parallel to the path of said carriage, andpin means on said housing engage the respective interlock lever to moveit out of the path of the respective locking bolt when the respectivefuse carrier is slid to its fully closed position.
 7. Switchgearaccording to claim 1 wherein guide means on said housing and on saidcarriage interfit with said fuse carriers to direct accurately each fuseinto engagement with the set of fuse contacts individual thereto whensaid fuse carriers are moved to their closed positions.
 8. Switchgearaccording to claim 7 wherein an interlock lever is pivoted on each fusecarrier and is biased with respect to the locking bolt thereon into itspath to prevent movement thereof to locking position, said guide meanson said housing engaging each interlock lever to move the same out ofsaid paths when said fuse carrier occupies its fully closed position. 9.Switchgear comprising a metallic housing, a plurality of sets of fusecontacts mounted in insulated spaced relation in said housing, aplurality of unconnected fuse carriers individually slidably mounted onsaid housing, a fuse carried by each of said fuse carriers for movementinto and out of contact engagement with a respective set of fusecontacts, a carriage slidably mounted on said housing independently ofand overlying said fuse carriers, coupling means on said carriage forselectively connecting said carriage to one or more of said fusecarriers for withdrawing said one or more fuse carriers and the fuse orfuses carried thereby from and returning the fuse or fuses to contactengagement with the respective set of contacts, a plurality of switchmeans in insulated spaced relation in said housing each of said switchmeans associated with a respective fuse for connecting said respectivefuse in and disconnecting said respective fuse from a circuit, and aswitch operating means for independently operating a respectivelyassociated switch means, and fuse interlock means on each fuse carrierarranged to prevent withdrawal thereof when the switch operating meansindividual thereto is in the closed position, and locking flipper meansoperated by each switch operating means is arranged to prevent closureof its switch means when the fuse carrier individual thereto iswithdrawn from said housing.
 10. Switchgear according to claim 9 whereinlost motion means between each switch operating means and the respectivelocking flipper means effect operation of the latter to permitwithdrawal of thE respective fuse carrier near the end of the openingstroke of said operating means for the respective switch means. 11.Switchgear according to claim 9 wherein each fuse carrier includes: apivotable locking bolt actuator, a locking bolt connected to saidactuator and movable by said actuator into and out of locking engagementwith said housing, and a cam receiving slot in said actuator; and saidcoupling means includes a manually operable locking cams pivotallymounted on said carriage individual to each said fuse carriers forentering the respective slot to engage said actuator to pivot saidlocking bolt actuator from and to locking position and make mechanicalconnection to the respective fuse carrier for withdrawing and returningthe same as aforesaid; and said switch operating means includes meansfor interconnecting each locking bolt for preventing movement of therespective locking bolt to unlocked position when said switch meansoccupies the switch closed position.
 12. Switchgear according to claim11 wherein said locking bolt has a transverse notch adjacent its distalend, and said means interconnecting said locking bolt includes a lockinglever for entering said transverse notch to prevent withdrawal of saidlocking bolt and the respective fuse carrier when said switch meansoccupies the closed position.
 13. Switchgear according to claim 12wherein said locking lever is L-shaped with one arm arranged to entersaid notch and the other arm pivoted at its distal end and mechanicallyconnected to the respective switch operating means.
 14. Switchgearaccording to claim 13 wherein said locking flipper means is a flipperbiased into the path of said other arm of said L-shaped locking leverfor preventing pivotal movement thereof when the respective fuse carrieris withdrawn to prevent opening of the respective switch means, and saidflipper is shifted out of the path of said L-shaped locking lever bysaid locking bolt when the respective fuse carrier is closed and saidlocking bolt occupies its locked position.